Compositing pine pollen derived carbon matrix with Na₄FeV(PO₄)₃ nanoparticle for cost-effective sodium-ion batteries...

Na super-ion conductor type material Na₃V₂(PO₄)₃ has been widely researched as the cathode of sodium-ion batteries (SIBs) in recent years, but the unsatisfying cost of Na₃V₂(PO₄)₃ impedes its wide application in SIBs. In this study, iron element is used to replace part of vanadium in Na₃V₂(PO₄)₃ to reduce its expense, and pine pollen is applied for the first time as a very effective carbon source to improve the performance of Na₄FeV(PO₄)₃. The fabricated composite material achieves a capacity of 105 mA h g^-1 under 0.2 C and fascinating cycling stability over 94 % under 2 C for 500 cycles and 98 % under 10 C for 1000 cycles. The excellent cycle performance is caused by the involvement of pine pollen that acts as a carbon matrix to enhance the electron conductivity and block the agglomeration of active material effectively, thus the well-dispersed nano sized Na₄FeV(PO₄)₃ shortens the diffusion path of sodium ion and gains a remarkable rate capability. Moreover, the distinguished reversibility during the charge and discharge procedures is ascribed also to the robust structure of Na₄FeV(PO₄)₃. This work provides an efficient route to realize the economic cathode material of SIBs with good performance.